PHS 7.3 Phono, £42,000
The PHS 7.2 and PHS 7.3 are dual-mono and symmetrical phono preamplifiers, featuring JMF Audio’s unique precision balanced input stage design and innovative ALP and ALP-EM linearization technologies. These phono preamplifiers can handle up to 2 (PHS 7.2) or 3 (PHS 7.3) tone-arms or record players. Their advanced hand-calibrated balanced input stage and high gain take full advantage of low-level moving coil cartridges, without the need for step-up transformers.
The innovative input module interfaces provide 16 resistive and 16 capacitive loads for each input and corresponding cartridge, for precise dampening and tuning of the upper range of frequencies to achieve a linear overall response. The load settings are assigned to each input which allows seamless switching from one tone-arm to another. The record collector oriented PHS 7.3 features a special mono mode and three optimized alternative compensation curves for the enjoyment of pre-RIAA era recordings.
JMF Audio products are designed to be references and to last. The base of these instruments is safe and modular. Upgrades are proposed for the original owner to take advantage of the results of our continuous research and development efforts, without the need for product change
JMF WRITES:
“The PHS 7.3 is intended for the most demanding vinyl record lovers and record collectors who wish to enjoy the early vinyl mono recordings without compromise.
The alternative curves:
The alternative Columbia, Decca and AES curves are easily selected from the lever on the front panel. The processing takes advantage of the JMF Audio passive components that are part of the RIAA circuit, without affecting it, thus guarantying the highest quality. The JMF Audio implementation of the alternative curves is named ALP-EM for Enhanced Matrix and is controlled by a dedicated custom programmed logic circuit. This unique implementation has also been registered for intellectual property. The alternative curves respect the three original parameters (turn-over, roll-off and bass shelf). For convenience, switching from one curve to another is made while retaining the same output level.
The mono mode:
For the music-loving record-collectors to enjoy the early vinyl mono recordings without compromise, the PHS 7.3 features a unique mode, activated by the extreme right button of the front panel, labeled as Mono. This mode takes full advantage of the dual-mono concept of the PHS 7.3, by reducing the overall noise, enhancing the rendering with stereo cartridges (without any change on the cabling) and obviously getting the most out of mono cartridges, vintage or cutting-edge. In mono mode, the audio signal is equally balanced to the left and right stereo outputs. Another challenge taken up, no additional electronic circuits are involved for the mono mode of the PHS 7.3 phono preamplifier, ensuring total transparency without change in performance.
Optimized MC inputs:
The PHS 7.3 features optimized inputs for MC cartridges. The resistive loads are also of lower values.
“The JMF Audio PHS 7.3 flagship phono will become a legend. I must deliver an in-depth writeup of it paying respect to the intellectual prowess of Laurent and Arnaud. The phenomenal delivery of musicality is picturesque and radiant. It earns a permanent place in our lab.”
When micro groove vinyl records were introduced in the late 1940’s, most record companies and their mastering facilities already applied recording curves to cut records masters. By reducing the levels in low frequencies and increasing the levels in high frequencies, the groove’s width was narrowed and evened over the bandwidth. This allowed more music to be recorded on the disc and lead to less overall distortion thanks to reduced cutter and pickup excursions. Applying the inverse curve at playback would permit to recover the original tone along with reducing the perceived surface noise thanks to the low-pass effect.
However most record companies, American, English and European, applied proprietary curves before adopting, with more or less eagerness, the RIAA curve defined in the mid 1950’s.
Along with the introduction of the micro groove vinyl record, larger bandwidth microphones and recording equipment also became more widely used and high-fidelity audio emerged; allowing jazz and classical music icons to release recordings that have become of historical value.
Although playing back these valuable records is possible using a RIAA tuned phono preamplifier, the overall emotional content would fail to be translated to the listener due to incorrect tonal balance and its side effects.
A lot of information on historical recording curves and their application can be found and heard from record collectors and products manufacturers, but many sources tend to disagree or copy each other. Many beliefs also seemed unrealistic to us. Therefore, JMF Audio spent years studying the subject and the most relevant solution for a phono preamplifier to serve the music and the demanding record collectors.
Visiting record shops, seeking first pressing records from the 50’s and 60’s at sellers located in the US, UK, Europe, Hong Kong, Japan; seeking books and publications by past and present specialists; meeting with record collectors and discussing with re-mastering engineers from England and Germany… The JMF Audio records and books collections increased tremendously over the years, with countless accompanying notes and data.
Methods for determining the most suitable compensation curves, based on measurements and comparisons in JMF Audio’s studios, backed with statistics, were developed. These methods have been registered for intellectual property.
Weighting the results with the value of the records on musical and historical criteria, by artist, by label, it was concluded that only a few alternative curves could cover all cases of interest, while ensuring ease of use. These curves were labelled Columbia, Decca and AES.
According to our experience, some record companies could have announced RIAA compliance (printed on sleeves) earlier than actuality as our evaluations drew that the mastering remained made with a proprietary curve. Other record labels seemed to have released different records using different curves in relatively short periods of time.
With these alternative curves, it has been made possible to follow the career of major artists in the original tonality, with preserved intend and emotional move. Going through recordings from Frank Sinatra, Duke Ellington, Benny Goodman, Charlie Parker, Dave Brubeck, Louis Armstrong and many more requires the use of the four curves featured in the PHS 7.3. The alternative curves respect the three original parameters (turn-over, roll-off and bass shelf).
Registered owners will access a detailed list of suggested applicable curves according to the records label with estimated change-over date, records identification as well as guides through notions such as recording, mixing, mastering, pressing, re-pressing, licensing, re-issues, re-recording, re-mastering…
The alternative recording curve matching belonging to the mono records era, PHS 7.3 users will advantageously select the mono mode when applying alternative curves.
The JMF Audio PHS reference phono pre-amplifiers feature a dual mono design, fully balanced circuitry, short signal path, and rely on the innovative ALP linearization (Intellectual Property registration).
> ALP is a purely passive linearization filter that compensates for the RIAA recording curve with precision.
> ALP features zero distortion, infinite headroom, by design.
> ALP is sealed and shielded under a machined block of aluminum of Orose® grade.
> ALP is built around bespoke made components and JMF Audio made components.
> ALP is buffered by JMF Audio’s SSA Super Symmetrical Analog technology involving hand calibrated input and output stages.
In addition to the main aspects, the details are of significant importance regarding the musical result:
PHS 7.3’s dual mono design with JMF Audio’s proprietary PGP 24 carat gold analog printed circuit boards embedding the proprietary ALP-EM record linearization filters. Components are populated on the top and on the bottom of the boards for optimal signal traces length.
For improved immunity to vibrations, each channel’s assembly is mounted on its own sub-chassis and benefits from dedicated suspensions.
Each printed circuit board is made up of more than 700 parts.
Like a recording studio microphone:
A phono cartridge is an electromechanical component that converts variations in records’ grooves into variations of electrical signal. Similarly, a microphone converts variations of air pressure into variations of electrical signal.
Both these sensors are made of a coil that needs to be connected to a signal amplifier. The signals are of very low magnitude and need to be protected against electromagnetic interference before amplification. This is why microphones have always been connected through shielded balanced interconnections in the recording studio world. For cost reasons related to consumer applications and also because the original cartridges were of moving magnet type, phono interconnections have been widely made through un-balanced links with RCA connectors.
The greatest care should be taken with nowadays precision moving coil cartridges that output low level signals. Since phono cartridges are balanced by design, the JMF Audio PHS phono pre-amplifiers handle them as studio microphones:
The PHS phono pre-amplifiers take advantage of JMF Audio’s innovative and still unrivaled hand calibrated precision balanced input stage technology which allows up to 100dB of interference rejection and consequently protects the least micro detail of music picked-up from the record. Moreover, the calibration method integrates psychoacoustic criteria.
The interface is ideally made with a JMF Audio phono cable from the tone-arm’s through DIN to XLR or RCA (hot-cold) to XLR. Optionally the PHS pre-amplifier can be ordered with input IN1 wired as RCA for the tone-arms that feature an attached cable. The signal would take advantage of the balanced input stage as well.
Multiple inputs and optimal cartridge loading:
The PHS phono pre-amplifiers can handle several tone-arms or record players through dedicated inputs. The load settings are assigned to each input which allows seamless switching from one tone-arm to another.
Quite a few modern cartridges feature rigid cantilevers and tend to present an un-even response with a significant rise of magnitude at the upper frequencies. Low value resistive loading is commonly admitted as the only way to obtain an acceptable response from these cartridges. The JMF Audio PHS phono pre-amplifiers propose an alternative through combined resistive and capacitive loading for precise dampening and tuning of the upper range of frequencies and achieve a linear overall response. By releasing the constraints on the cartridge, the musical rendering shows greater openness and liveliness. The load value being dependent on the cartridge, the setting is located near the corresponding input, which ensures the shortest signal path. All inputs load settings are easily controllable at sight from the rear panel.
High gain:
The JMF Audio PHS phono pre-amplifiers feature as high as 75dB of gain for the modern moving coil cartridges that require more amplification. A lever on the front panel allows to adapt the gain to suit MM and MC cartridges, the overall system’s gain or the line pre-amplifier’s sensitivity.
Absolute phase:
To compensate from recordings made out-of-phase and/or to match with next amplification stages which balanced connections follow a former standard, the PHS phono preamplifiers feature an absolute signal phase control.
No additional electronic circuits or components are involved for absolute signal phase control in the PHS phono pre-amplifiers, ensuring total transparency without change in performance.
Subsonic filter:
Very low frequency content, usually due to record wrap, recording flaw or acoustic induced vibrations, may alter the musical rendering along with putting unnecessary high demand on the power amplification. Elimination of the lowest frequencies is made possible by activating the subsonic filter with the Filter push button.
The processing is purely passive and no additional electronic circuits are involved for the subsonic filtering in the PHS phono pre-amplifiers.
PHS 7.3 dual-mono phono pre-amplifier – Orose® silver
The PHS phono pre-amplifiers have taken advantage of the result of JMF Audio’s long researches on the sound neutrality of passive components, semiconductors and materials, as described in the pages related to the HQS power amplifiers. The JMF Audio PHS phono pre-amplifiers utilize selected and uncommon components for audio applications: instrumentation metal-case semiconductors, proprietary printed circuits boards substrates…
Due to the requirements for specific components from the aeronautic, aerospace and fast-train industries located in France, some companies have specialized in manufacturing custom parts. Thanks to our initial activities in high-frequency electronics, as told in the History of the Brand, we have collaborated with such specialists for over 30 years, which has allowed JMF Audio to obtain made to measure components and parts, especially passive, that best suited our criteria, for the music.
The JMF Audio’s proprietary PGP 24 carat gold printed circuit board substrate is incompatible with the automated processes. The hundreds of components populating both sides of the boards are hand mounted and soldered one by one by our specialized technicians using JMF Audio’s specific solder, under a magnifying glass. A process that requires skills and patience and results in the application of jewels manufacturing methods.
A total of 8 adjustment points are hand calibrated on each pre-amplifier after 100 hours of operation at the manufacture.
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The PLS linear power supply technology from JMF Audio is now part of the PHS phono pre-amplifiers. It is the result of over a decade of research and development on the mains current (PCD 302 and PCD 102). It is based on a dedicated and made to measure low-noise and low-vibration toroidal transformer of the same technology as the large transformers that have equipped the JMF Audio power amplifiers for long.
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The JMF Audio Instruments for the music® are entirely hand crafted in our workshops and pass stringent tests. Every manufactured pre-amplifier has been verified by listening in our studios after an operating period of over 100 hours and placed in comparison with our references.
The dual chassis design, with the Orose® enclosure made of 10 to 16mm thick anodized and brushed aluminum parts, lays on JMF Audio’s proprietary decoupling feet. Whichever the chosen anodizing color Silver or Black, the engravings are filled with rose-gold and the controls, inserted in guided cylinders for smooth operation, are precisely machined in solid blocks of steel. The toggle switches, individually housed in a metal frame, are made in France to JMF Audio’s specifications.
Each PHS phono pre-amplifier is delivered with an Owner’s Manual containing the warranty terms and registration information.
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Number of outputs
3 (2 balanced, 1 un-balanced)
Number of inputs
3
Original input module types
MC optimized (x2) and MC/MM (x1)
Analog circuit board technology
PGP 24 carat gold
Linearization filter type
ALP-EM (Enhanced Matrix)
Linearization passive components
Reference grade (handmade operations at the JMF Audio’s manufacture)
Recording curves
RIAA, Columbia, Decca, AES
Mono mode
Yes
Subsonic filter
Yes
Hand calibrated inputs and outputs
Yes
Technical specifications:
Input impedance range
defined by input module type and settings
RIAA deemphasis curve conformance
+/- 0.05dB (1k..20kHz), +/- 0.1dB (20Hz..20kHz)
Interference rejection on the inputs
100dB typ.
Output impedance
Gain range
50 ohms
0, -10, -20dB (ctrl. with front panel switch)
Maximum gain output/input
75dB (low level MC cartridge)
Mono mode
dual mono (ctrl. with front panel button)
AC mains power supply
100V, 120V, 220-240V AC – 50/60Hz (according to country of destination), version B
Power consumption
<25W, version B
Net weight
14 kg (31 lbs), version B
Finishes
Silver or Black anodizing
XLR metal case, gold contacts | RCA metal case, gold contacts
Connectors
200mV (typ. MM cart), 20mV (typ. MC cart), Gain min
Maximum input level
10V (+22dBu) into 10k ohms load
Maximum output level
1Hz..150kHz (intentionally limited for RF immunity)
Global circuits bandwidth
>96dBA (10V output, Gain min, typ. MC cart, IN1)
Signal to noise ratio (SNR)
<0.002% (10V output 1kHz, Gain min, BW.20kHz)
Total harmonic distortion (THD)
>100dB (10V output 1kHz, Gain min)
Channel separation
-12dB/oct, 13Hz (ctrl. with front panel button)
Subsonic filter
0 / 180° (ctrl. with front panel switch)
Phase range
Orose® up to 16mm thick machined anodized aluminum, machined steel buttons and rose-gold
Enclosure
482 wide (front panel) x 320 deep x 106 high mm including feet (19” x 12.6” x 4.2” high)
Dimensions
Measurements with Audio Precision APX555 equipment. Voltage values are RMS. Specifications are based on the manufactured products at date of writing and may change with product evolution.
Versions history:
B
The PLS linear power supply technology from JMF Audio is now part of the PHS 7.3 and PHS 7.2. It is the result of over a decade of research and development on the mains current (PCD 302 and PCD 102). It is based on a dedicated and made to measure low-noise and low-vibration toroidal transformer of the same technology as the large transformers that have equipped the JMF Audio power amplifiers for long.
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